Interlocking building blocks used in the construction of mortarless walls typically have projections on an upper surface of the block and have corresponding recesses on a lower surface of the block, the projections of one block being adapted to be received in, and interlock with, the recesses of an overlying block, thereby obviating the need for any securing mortar between courses. Such blocks may be used to construct building structures and are also used with increasing popularity in developing countries to reduce building costs by decreasing the time required to complete the structure. Walls made from interlocking blocks are also gaining acceptance in zones having seismic activity.
The corner and end blocks in accordance with the invention are intended to be used with a system of interlocking building blocks of the kind which is fully described in Applicant's co-pending U.S. application Ser. No. 08/850,105, the contents of which are incorporated herein by reference. In constructing walls using mortarless blocks, it becomes particularly important to reinforce the resulting structure by grouting the cavity defined inside vertically-adjacent blocks with concrete reinforced with structural steel bars. Such reinforcement is particularly desirable at corners, at wall ends, as well as at spaced locations along the length of a wall structure.
While interlocking building blocks are known, there are surprisingly few block structures which are specifically designed to maximize strength at wall ends and corners.
Important factors in maximizing strength are that the block define a relatively large cavity so as to be adapted to receive a proportionately large volume of grout; that the block have means to positively locate its position relative to other blocks so that it will not shift after being laid; and that the block have means to readily receive and locate structural steel reinforcement bars. Without such features, the strength and reliability of the resulting building structure are compromised.
U.S. Pat. No. 4,372,091 to Brown et al teaches an interlocking block structure having first and second face shells connected by spaced bridge portions having projections on a top surface and corresponding recesses on a bottom surface. The ends of the face shells may be closed by vertical inserts. The resulting structure has a very small grouting cavity which is formed between the insert and the proximate bridge portion. Positive location of the block when disposed at a corner is provided by an auxiliary bracket. There are no provisions for reinforcement bars.
U.S. Pat. No. 3,888,060 to Haener provides a specialized end block for use at corners and wall ends which has a larger grouting cavity than Brown et al, but which, likewise, cannot accommodate reinforcement bars without breaking an upwardly-extending tang portion which then allows the block to shift because there are no additional interlocks provided.
U.S. Pat. No. 4,319,440 to Rassias et al provides a large grouting cavity and structure to readily receive reinforcement bars through notches formed in outer and inner shells for the block, but there is no provision for interlocks to hold the blocks in position relative to each other until a reinforcement bar is placed in position and the blocks are grouted.
While all of the above-described blocks have some features which are desirable, there is a need for a block which will advantageously overcome their respective drawbacks.
An object of this invention is to provide a building block suitable for use at corners and end wall applications which will strengthen the resulting wall structure so that it is less vulnerable to collapse in adverse situations.